You may not have anything to eat on the plane.
We encountered this situation when flying home from Switzerland on British Airways about 15 years ago. They gave us vouchers to spend on food at each airport before boarding. In Zurich we spent the vouchers on chocolate. 🍫 🍫 🍫 But for the long-haul flight from Heathrow to Seattle we needed real food. There were thousands of people in the airport all trying to acquire food before their flights, but Starbucks in T5 came through, repeatedly stocking the cold case with assorted sandwiches.
The flight was noisy, with all the rustling paper wrappings, and messy, as the flight crew did not circulate and pick up trash often enough. And no wine was served. But we survived.